Smooth PWM signal

Hello, forum! I have been working on a project that lets me debug analog and digital sensors for the NXT robotics system. During the development, I had the need to convert digital to analog signals that could be read by an ADC unit. I found it very difficult to find the information on the subject, and now that I've found it, I thought I might share some informational links for smoothing out PWM signals.

Note, I didn't write these.

Websites:

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/filcap2.html

Here's hoping that others can find the information on this topic more easily than I did.

Maybe you add it to the Arduino Wiki as a quick tutorial? Write about everything you know, others may come past and edit it to make it better, then its there for us all.

Here is another one that discusses the requirements of a filter on a PWM output:-

http://www.thebox.myzen.co.uk/Tutorial/PWM.html